Process for the production in watery emulsion of blends of polyvinylic alcohols and respective products obtained

A process for the preparation of an aqueous emulsion of two or more polyvinyl alcohols (PVA) with different saponification numbers (NS) for use in the production of polyvinylchloride (PVC-S) in an aqueous suspension comprising the steps of:

• i) utilizing at least a first polyvinylacetate (PVAc) with molecular weight between 30 and 110K, to carry out the alcoholysis of the PVAc to reach NS values between 598 and 135 in the presence of ethyl alcohol or methyl alcohol with acidic or basic-catalyst;
• ii) loading from 0.1 to 5 times parts by weight with respect to the first PVAc, of a second PVAc having a molecular weight between 10 and 90K;
• iii) stopping the alcoholysis such that, in a final alcoholic solution, the respective PVA are perfectly mixed in order to obtain;
• a) at least a first PVA, with NS between 280 and 95, soluble in water;
• b) at least a second PVA, with NS between 598 and 312, insoluble in water;
• iv) and distilling during the alcoholysis or at its termination, the residual solvents by adding water after the alcoholysis so as to obtain coagulation in water of the second PVA in the form of microparticles with a granulometric distribution between 0.1 um and 10 um.